The present invention relates to a backup apparatus and a backup method for backing up a plurality of files stored in a disk device as an auxiliary storage apparatus, as well as to a file reading apparatus for reading such plurality of files from the auxiliary storage apparatus, and, for instance, can be suitably applied to a file server.
In recent years, a file management function referred to as a file system is being loaded in many computer systems. A file system comprises a directory for hierarchically managing files in order to facilitate the management of files of programs and user data. A file system includes a special directory known as a root directory to become the apex of the hierarchy of files and directories, and the files and directories stored in the file system can be traced back from the root directory.
A file system creates, per file, management information referred to as an inode (hereinafter referred to as “file information”) that is configured from attribute information such as the file name, creation date, last update date, last referral date and access authority, and address information showing in what position of the storage area provided by the auxiliary storage apparatus the data of such file (file data) is being stored, and manages the respective files based on the file information. The file information of the respective files is stored and retained in a dedicated storage area called a super block that is provided separately from the storage area storing the file data.
The file system also creates, per directory, management information referred to as an inode (hereinafter referred to as “directory information”) that is configured from attribute information such as the directory name, creation date, last update date, last referral date and access authority, and internal management information such as the pointer to the inode of the respective files and respective directories existing in that directory, and manages the respective directories based on the directory information. The directory information of the respective directories is also stored and retained in the foregoing super block.
When a file is newly created, a file system creates file information of such file, writes the file information and data into the corresponding storage areas, respectively, and adds a pointer to the file information of such file in the directory information of the directory to which the file was created.
Details of the foregoing system are described in pp. 679-692 of “Computer Architecture A Quantitative Approach,” Volume 3 (ISBN 1-55860-724-2), (USA), Co-written by John Hennessy and David Patterson, Elsevier, Chapter 7; Non-Patent Document 2.